Why is Novel Coronavirus highly contagious?

Why is Novel Coronavirus highly contagious?

Last Reviewed : 12/17/2020
Why is Novel Coronavirus highly contagious?

Coronavirus pandemic started in Wuhan city of China but is rapidly spreading all over the globe. In few countries, number of cases are doubling within a day or two. Along with the United States, few European countries have a major impact. There are multiple reasons why Coronavirus is spreading rampantly.

  • Spreading the virus before developing symptoms: When people are exposed to Coronavirus, it usually takes anywhere from 2 to 14 days before symptoms develop. The median time to develop symptoms is around 5 days. Most of the affected persons start spreading the virus after symptoms appear. However, some affected individuals start spreading the virus even before symptoms develop. This is called as asymptomatic carrier state. It is also possible that few affected individuals may not even develop any symptoms at all. They may remain asymptomatic throughout the course of the illness. Earlier in the course of this pandemic, it was thought that the role of asymptomatic spread was minimal. However, as it became more rampant, it became obvious that asymptomatic spread is playing a major role.
  • Touching fomites: Fomites are the objects or materials that likely spread the infection. Cell phones, utensils, clothes, furniture, bathroom doorknobs, taps are some common fomites known to spread the disease from one person to another. Coronavirus may last from few hours up to 9 days depending on the type of the surface. When infected people cough or sneeze, Coronavirus present in the droplets may settle down on the fomites. When a healthy individual touches the fomites and also touches his or her nose, eyes or mouth, it spreads rapidly to the healthy individual. On an average, we touch our face 20-30 times in an hour. It is extremely difficult to avoid the urge to touch the face as it happens subconsciously. It is very important to wash hands thoroughly and avoid touching the face.
  • Airborne spread: Based on the study published in the New England Journal of Medicine, Coronavirus can remain viable in aerosols (small particles floating in the air) for about three hours. When an infected person coughs or sneezes few aerosols are produced depending on the intensity of cough and the amount of respiratory secretions. Epidemiologically, airborne spread in the communities is a rare phenomenon but it is definitely possible. When aerosols are generated in a larger quantity which can happen in hospitalized patients being intubated, on BIPAP machine or receiving nebulization, Coronavirus can definitely spread by air. It is very important not to enter the room for several hours when an infected person is receiving nebulizations.
  • Public places and traveling: Most of the community based spread occurred in people who traveled to other places. It is important to avoid unnecessary travel as it can spread in the airports, train and bus stations. Avoiding public places is also very important as it can spread from one person to the other. Based on the study published in Biosci Trends, as we spend more time in the crowded areas, the risk of getting infected goes higher. The study recommends not to be in the crowded areas for more than 2 hours.



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  • Biosci Trends. 2020 Mar 19. doi: 10.5582/bst.2020.01482. Analysis of COVID-19 infection spread in Japan based on stochastic transition model. Karako K et al.
  • Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1. Van Doremalen et al. N Engl J Med. https://doi.org/10.1056/NEJMc2004973
  • Biosci Trends. 2020 Mar 19. doi: 10.5582/bst.2020.01482. Analysis of COVID-19 infection spread in Japan based on stochastic transition model. Karako K et al.

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